1. Field of the Invention
The present invention relates to a novel compound of cerium (IV) and to a process for the preparation thereof. This invention more especially relates to a novel compound of cerium (IV) that is readily dispersed in water.
2. Description of the Prior Art
It is known to this art, from the Kirk-Othmer Encyclopedia of Chemical Technology, 2nd Edition, Vol. 4, p. 850, that a hydrated ceric dioxide corresponding to the formula CeO.sub.2.x H.sub.2 O, wherein x is a number ranging from 0.5 to 2 and which is present in the form of a gelatineous precipitate, may be prepared by the addition of sodium or ammonium hydroxide to solutions to ceric salts.
It has also been proposed to this art, according to French Patent No. 2,482,075, to prepare a compound of cerium (IV) which is dispersible in water by dispersing, in an aqueous medium, a hydrate of an essentially dry oxide of cerium (IV), the same having been subjected to a heat treatment at a temperature of from 200.degree. C. to 450.degree. C., in the presence of a disintegrating agent, in particular nitric acid. Heating in the presence of a disintegrating agent effects the disintegration of the aggregated crystallites into the hydrated cerium (IV) oxide, thereby producing a dispersible cerium compound.
It is noted in this '075 patent that the preparation of a hydrate of cerium (IV) oxide may be carried out by precipitation beginning with a cerium salt; thus, for example, a high purity cerous carbonate may be dissolved in a solution of nitric or hydrochloric acid to obtain a neutral solution of cerous nitrate or chloride, which is then oxidized with NH.sub.4 OH/H.sub.2 O.sub.2 to obtain the hydrate of cerium (IV) oxide.